OpenRouter after Stripe: 5.5% fee, provider drift, RTK, litelm

Stripe is buying OpenRouter: announced on 19 August, reported at over $7 billion, closing expected within weeks. The announcement promises the same product, name and roadmap, with routing decided by what is best for the user. The visible price today is a 5.5% platform fee on pay-as-you-go credits, 8% on the Business plan, and bring-your-own-key is free up to $25,000 of list-price inference a month, 5% after that.

Two write-ups from the same fortnight measured the costs that fee does not show.

One operator, running about 18 million messages with roughly a third on open models through OpenRouter, tested the providers behind a single model id. On OpenRouter's own per-provider board, DeepSeek V4 Flash 0731 scored 90% on GPQA and 81% on TAU-Bench Airline at DeepSeek itself, and 75% and 58% at another host serving the same weights. Some hosts accepted reasoning.effort and ignored it, some returned HTTP 200 with empty content, and filtering for declared fp8 did not predict quality.

The other measured RTK, the terminal output compressor with 79k stars, across 1,740 Terminal-Bench 2.1 attempts and more than $1,500 of tokens. The bill fell 5% with Claude Code on Fable 5.0 and rose 5% with OpenCode on DeepSeek V4 Pro. Almost all of the Fable saving came from one task, and rtk gain reported 349 million tokens saved on runs that cost more.

And for anyone who only wanted the call path, litelm cuts LiteLLM down to routing and message translation: about 2,900 lines and two dependencies.